Vehicles with hybrid drives are known from the prior art. Hybrid drives have two or more different drive sources, while drive trains with a combustion engine and one or more electric engines as parallel hybrids or as mixed hybrids have gained broad acceptance. These variants have in the force flow a substantially parallel arrangement of the combustion engine and the electric drive and thus permit both an overlaying of the driving torque and an activation with solely combustion engine drive or solely electric engine drive.
Document DE 10 2010 030 573 A1 made known a hybrid drive with an automatic shift gear unit, which comprises a combustion engine, which is drive-connected to at least a first gear input shaft, with an electric drive, which comprises at least an electric engine, which is drive-connected to a second gear input shaft, with at least one countershaft, with loose wheels and fixed wheels arranged in several gear set planes, with several gear shifting devices and with a gear output shaft. To permit great variability with regards to a gear set concept as well as the distribution and the number of electric and combustion engine gears, to keep construction expenses and costs low and to ensure efficient and comfortable operation, it is envisaged that the two gear input shafts are arranged coaxial with each other, and that a gear shifting device in one of its shifting positions connects the two gear input shafts to one another in a drive-effective manner, and in another shifting position shifts a gear. This permits a partial gear coupling which couples the two input shafts, the hollow shaft and the solid shaft, to one another without a gear being shifted.
To achieve maximally effective operation of the hybrid drive, drive strategies are used, which employ the electric drive in a flexible manner depending on the situation, for example for start-up, as a starter generator or as a generator for power generation. A device for a drive train of a hybrid vehicle is known from document DE 10 2010 063 582 A1, which device has a planetary gear comprising the elements carrier, a sun gear and a ring gear, wherein a first element of these elements of the planetary gear serves to firmly connect a first gear input shaft of a first partial gear of a gear unit, and wherein a second element of these elements of the planetary gear serves to firmly connect an electric engine of a hybrid drive, with a first shifting element, by means of which a third element of these elements of the planetary gear in a first shifting position of the first shifting element can be connected to a second gear input shaft of a second partial gear of the gear unit, to which a combustion engine of the hybrid drive can additionally be coupled, and in a second shifting position of the first shifting element can be connected at the housing side or stator side, and with a second shifting element, by means of which in the case of an engaged second shifting element both gear input shafts of both partial gears can be coupled to one another and in the case of a disengaged second shifting element both gear input shafts of both partial gears can be separated from one another. This permits an electro-dynamic start-up and also electro-dynamic shifting. The electric engine can additionally be used as an integrated starter generator.